Transforming means



Aug. 1, 1939.

C. A. SABBAH ET AL TRANSFORMING MEANS Filed June 5, 1937 Fig.6.

SECOND/ll? Y CUR/TE 1V 7' Alf? GAP //1/ 60/715- VOLTA 6E VOLTAGE CURRENT 3 Sheets-Sheet 2 Fig.7.

AIR GAP //V CORE OUTPUT VELTAGE OUTPUT CURRENT INPUT VDLTAGE M M0 a4 all 150 100 20a 11a Fig.9.

.VOLTAGE lnventorsl Car-nil A. Sabbah,Deceased by William A. Dodge, Administrator" logsle W. Morton,

ttorneg' Aug. 1, 1939. c sABBAH AL 2,168,173

TRANSFORMING MEANS Filed June 5, 1937 3 Sheets-Sheet 5 JECI/WMR Y CURRENT Inventors: Cami! Afiabbah, Deceased by William A.Dodge, Administrator L gsle W. Mor on,

Attorne alternating current circuits.

Patented Aug. 1, 1939 UNITED. STATES PATENT.- "OFFICE 2.168.113 mnsr'ormmc MEANS Application June 5, 1937, Serial No. 146,660 izouums.v (Cl.'17197) The invention relates to electric translating apparatus and more particularly to electric translating apparatusfor transmitting energy between constant voltage alternating current circuits and constant current alternating current circuits.

.Heretofore there have been devised numerous arrangements for effecting the transfer of energy between constant voltage alternating current circuits and constant current alternating current circuits. Some of these arrangements have ineluded devices having relatively movable parts for effecting this transformation and other arrangements have employed a plurality of reactances of opposite sign, such as inductances and capacitances, for effecting this transformation. In view of the recent advances in electric power transmission, there has-beenevidenced a decided need for transforming apparatus to facilitate the transformation of constant voltage alternating current to alternating current of constant value by apparatus having only stationary elements and by apparatus employing only a minimum number of parts, affording thereby an economical apparatus susceptible of a wide diversity of use and being of an inexpensive construction. For example, there has been evidenced a need for apparatus of this type for use in connection with the electric power transmission and distribution system disclosed and claimed in U. S. Letters Patent 1,990,758, granted to Charles W. Stone, February 12, 1935, and assigned to the assignee of the present application.

It is an object of the invention to provide a new and improved electric translating apparatus.

It is another object of theinvention to provide a new and improved transforming apparatus for effecting the transfer of energy between constant voltage alternating current circuits and constant current alternating current circuits.

It is a further object of the invention to provide' a new and improved transformer for effecting transfer of energy between constant voltage alternating current circuits and constant current alternating current circuits whichis devoid of relatively movable parts and which is simple and reliable in construction and arrangement.

In accordance with the illustrated embodiments of the invention, there is provided a new and improved transforming device for effecting transfer of energy between constant voltage alternating current circuits and constant current The transforming device comprises a pair of spirally wound, electrically insulated windings preferably arranged to he a mutual inductance substantially equal to the se i inductance of the windings and being proportioned so that there are provided mutually disposed surfaces in proximity to afford interwinding capacitance which together with the inductance constitutes a tuned circuit to effect the desired transformation. The windings are 1.11-- mensioned so that the tuned circuit resonates to the frequency at which the device is intended to operate, or, in other words, the device is arranged to resonate to the frequency of the voltage or of the current of the associated circuits. The windings may be associated with a magnetic core structure and the magnetic core structure may be modified or dimensioned to control the output or the input characteristic of the device. For example, the core structure may be constructed to have an air gap to obtain the desired operating characteristics. In a modified embodiment of the invention an auxiliary coil, energized with direct current, is employed to control the saturation of the core member and to control thereby the value of the constant current output which is maintained.

For a better understanding of the invention, reference may be had to the following description taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claims. Fig. 1 diagrammatically illustrates an embodiment of our invention as applied to an arrangement for effecting transfer of energy between a single phase constant voltage alternating current circuit and a single phase constant current alternating current circuit. Fig. 2 represents diagrammatically an arrangement of the windings and the insulation of the embodiment of the invention shown'in Fig. 1. Fig. 3 represents the equivalent electric circuit of the arrangement shown in Fig. 1. Fig. 4 diagrammatically shows another embodiment of our invention as applied to an arrangement for .effecting transfer of energy between a. three phase constant voltage alternating current circuit and a three phase constant current alternating current circuit, and Fig. 5 represents the equivalent electric circuits and shows the manner in which the windings of Fig. 4 are to be connected to associated circuits. Figs. 6, '7, 8 and 9 represent characteristics thereof. e e

Referring now to Fig. 1' of the accompanying drawings, the invention is diagrammatically shown as applied to a transformingdevice or a transformer I for effecting transfer of energy between a single phase constant voltage alternating current circuit and a single phase constant current alternating current circuit. The transformer I includes a pair of spirally wound windings which may be associated with a mag netic core member 2...- The core member 2, if desired, may be constructed with a high reluctance portion, such as an'air gap 2, to obtain a certain desired operating characteristic. The ar-, rangement of the windings may be better under-. stood by referring to the expanded view of Fig. 2. It is to be noted that the windings which have been termed primary winding and secondary winding are electrically separated from each other by the use of suitable insulation, and that a primary winding 3 is provided with a terminal 4 and that secondary winding 5 is provided with a terminal 6. The primary winding 3 and secondary winding 5 are dimensioned and disposed relative to each other so that there are provided sufficient areas thereof in proximity to establish a substan tial inter-windingcapacitance. Furthermore, the windings are arranged so that the mutual in-- ductance thereof is substantially equal to the self inductances. The inductance of the windings 3 and 5 and the interwinding capacitance of these windings constitute in eflect a monocyclic square.

The primary winding 3 and the secondary wind ing 5 are also provided with terminals 1 and 8; respectively, which are connected to the other ends of the respective windings.

The equivalent electric circuit of the arrangement diagrammatically illustrated in Figs. 1 and 2 is shown in Fig. 3. The windings shown in Fig. 3 and the taps or terminal connectionsv have been assigned reference -numerals corresponding to the arrangements shown in Figs. 1 and 2. The

transforming device of Fig.3 is shown'as being connected to effect transfer of energy betweena constant voltage alternating current circuit 9 and a constant current-alternating current circuit I0. Electrically opposite terminals of each of windings '3 and 5 are connected to different circuits. For example, terminal 4 of winding 3 is connected to circuit 9, while terminal I of winding 3 is connected to circuit I0; and terminal Ii of winding 5 is connected to circuit I 0, while terminal 8 of winding 5 is connected to circuit 9.

The capacitances II represent the distributed inter-winding capacitance of windings 3 and 5 and the capacitances I2 and I3 represent the resultant or effective inter-winding capacitance of these windings. The capacitances I2 and I3 may be considered as being effectively connected in series relation with the windings 3 and 5 and the associatedcircuits 9 and Ill. The inductance of the windings 3 and 5 and the effective interwinding capacitance represented by the capacitances I2 and I 3 constitute in effect a monocyclic square.

The operation of the embodiment of the invention diagrammatically shown in Fig. 1 may be best explained by considering the equivalent circuit shown in Fig. 3. Let it be assumed that it is desired to supply to the circuit III an alternating current of constant value from the constant voltage alternating'current circuit 9. By virtue of the arrangement of the windings 3 and 5, the effective inter-winding capacitance as represented by capacitances I2 and I3 constitutes, together 2,1es,17e

with the mutual inductance of windings 3 and I,

maintain the output current at a substantially constant value; and, conversely, as the resistance of the load circuit increases, the voltage impressed thereon by the transforming device I will correspondingly increase to maintain the current constant.

The operation of the embodiment of the invention shown in Fig. 1 may be better understood by referring to the operating characteristics shown the secondary current, that is, the current in winding 5 under variable load conditions. Curve A represents the secondary current under varying load conditions with a certain value of applied primary voltage when the core member is provided with an air gap, and curve B represents the secondary current when the applied voltage is reduced to approximately one half that applied under the conditions represented by curve A. Curve C represents the secondary current under varying loadconditions when the primary voltage applied is approximately that under the conditions represented by curve -A and when the core member does not have an air gap.

The curves of Figs. 7, 8 and 9 will be of assistance in explaining the relationships betweenthe elements of the inductive devices shown in Figs.

1 and 4. Although to effect transformation of constant voltage alternating current to alternatplicants invention the device is operated at a constant frequency, it is believed that the characteristics as shown in Figs. 7, 8 and 9 as functions of an applied voltage of variable frequency will be helpful in understanding theinvention. Curves D, E and F represent theoutput-current, output voltage and the input voltage as functions of the frequency of the line voltage for the circuit arrangement in Fig. 7a, where an impedance is connected in series relation with the line and serves as a protective means. Curves- G and H of Fig. 8 represent the primary and secondary voltages, respectively, as functions of the frequency when an air gap is used in the core, and curves J and K of Fig. 9 represent the primary and secondary voltages, respectively, as functions wound coils I8, 19 and-20,,respectively. Each of the coils l8, I9 and 20 comprises a,pair of electrically insulated and spirally wound windings, such as windings 3 and 5 shown in Fig. 2. Each of the windings or conductors of coils I8, I3 and 20 is provided with two taps or terminals, one at the beginning and the other at the end of the winding. For example, the,primary winding of coil I8 is provided with terminals 2| and 22 and the secondary winding isprovided with terminals manner, coils I8 and 20 are 23 and 24. In like in Fig. 6. The curves A, B and C represent having three legs I5, I6 and I!- about which are provided with similarly connected terminals 2528 and 29-42, respectively.

The circuit diagram of Fig. 5'represents the connections of the transforming device 01 Fig. ,4 when it is vdesiredto eflect transfer of enemy from constant voltage alternating current circuits 33, 34, and 35 and constant current alternating current circuits 36, 31 and 38. It, of course, will be well understood by those skilled in the art that the circuits 33-35 and 36-48 may be connected in the usual way to three phase alternating current circuits when it is desired to effect transfer of energy between three phase systems.

The embodiment of the invention shown in Figs. 1 and 4 operates to transform constant voltage alternating current into alternating current of constant value, or vice versa. One way in which the operation of the embodiment of our invention may be analyzed is as follows: The inductances of the windings 3 and 5 are assumed to have no individual leakage'reactance. This assumption is justifiable whether the windings i- ==pb n b +b induced in each coil is identical. To facilitate 1 r v are on one core or on two cores, since the flux the analysis of the operation of the arrangemerit, the elemental reactor currents or the currents transmitted through the elemental inductances of windings 3' and 5 may be represented by or, an (Zn-2, an-l, a, and the (currents which flow by virtue of the elemental interwinding capacitances may be represented by b1,

b2 bn. The inductive reactance for the elemental portions of winding 3 will be represented as 021, and the inductive reactance of the elemental portions of winding 5 will be represented by 22. The voltage of the constant voltage alternating current circuit 9 may be represented as E, and the current of circuit 9 may be represented at as.

Z may represent the impedance of load circuit i0, and in may represent the current transmitted thereto. Kirchoffs equations may be written, reierring to Fig. 3, assuming that there are n portions of the windings between the elementary I interwinding capacitances. On' this assumption, there are n reactors or inductances on each winding and n+1 capacitances. By multiplying the equations by j to simplify, and assuming 1; is an even number, the voltage equations may be written as:

.Boiving for l' b (t in this last equation and substituting in those above yields a new set of equations from which can be found and substituted. This operation is repeated until one Equation 24: remains. Letting By substituting in from Equation 1 in Equation 211, produces finally:

Using the equations of Groups 4 and 5, the currents represented by the a quantities can be eliminated from Equation 2and-the groups of Equations 3, as follows:

If he is to be independent or z:

In order to advance the analy:-is from this point, it is necessary to study Equation 7, particularly the 1(1)); The object, of course, is to let I 60 axis. I While the invention has been shown and de- .n become infinite.

of n, it will be seen that as n approaches infinity,

p approaches Y Substituting from Equation 7 into the lefthand side of Equation 6 produces, noting that- The above analysis proves that the current transmitted to circuit In is independent of Z for the proper frequency, and further shows that each small element is and operates as a monocyclic square.

In Fig. 10 there is shown another embodiment of our invention in which a magnetic condition of the core structure is controlled, toeffectcontrol of the value of the constant current which is maintained. The arrangement of Fig, 10 issimilar in many respectsto that of Fig. 1 and corresponding elements'have been assigned lilre ref- 40 crence numerals. 'A core member 39 is also pro vided with an agency, such as a coil 40, which controls the saturation of the core member 39 to establish the value of constant current which will be maintained by the device. The coil 40 may be energized from any suitable source of direct current II and a circuit controlling means,

such as an adjustable resistance 42, may be used to control the current supplied to coil 40. It is to be understood that the resistance 42 may manually or automatically operated.

The curves of Fig. 11 represent the output current of the'arrangement of Fig. 10 under varying load conditions. Curve L represents the output current when there 'is no current in coil 4 0, and

curves M, N and 0 represent this characteristic with increasing values of direct current in coil 40.

The normal range of operation of the device will be within the region lying between the horizontal line entitled Full load voltage and the abscissae scribed as applied to a particular system of connections and as embodying various devices dla-" grammatically shown, it will be obvious to those as skilled in the art that changes and modifications may be made without departing from the invention, and it is therefore, the aim in the appended claims to.cover all such changes and modifica-y tions as fall within the true spirit and scope of the 70 invention.

What is claimed as new and desired to secure by Letters Patent of the United States is:

1. In combination, an alternating currentsupply circuit, a load circuit, and adevice compris 75 ing a pair of electrically insulated windings being each'having a pair of terminal connections, elecwound in mutual inductive relation and being disposed relative to each other-to have sufiicient inter- -winding capacitance which together'with said inductance constitutes a tuned circuit resdnant to the freqency of said supply circuit for,

effecting transformation of constant voltage al- 'ternating current to-alternating current of constant value.

" 2. In combination, an alternating current supply circuit, a load circuit, and a transformer comprising a magnetic core structure and a pair of electrically insulated windings wound about said core structure and arranged to have a substantial mutual inductance, said windings being wound to minimize flux leakage therebetween and having sumcient inter-winding capacitance which together with said inductance constitutes a tuned circuit resonant to the frequency of said supply circuit for efiecting transformation of constant voltage alternatingcurrent to alternating cur-.

rent of constant value.

' 3. In combination, an alternating current supply'circuit, a load circuit, and a device comprising a pair of electrically insulated windings wound to form an inductance and being positioned rela-' tive to each other to minimize flux leakage therebetween, said windings having mutually disposed surfaces of a magnitude suflicient to providea capacitance which together with said inductance constitutes a tuned circuit/ resonant to the frequency 'of said' supply circuit for transforming constant voltage alternating current to alternating current of constant value.

4. In combination, a constant voltage alternating current circuit, a second .circuit, and a device interposed between said circuits for transmitting alternating current of constant value to said second circuit from said constant voltage alternating current circuit comprising a pair of electrically insulated windings being wound to have a substantial mutual inductance and having sufficient inter-winding capacitance to constitute a tuned circuit resonant to the frequency of said constant voltage circuit.

a 5. In combination, a constant voltage alternating current circuit,ua second circuit, and a device for transmitting' alternating current of constant value to said second circuit from said constant voltage alternating current circuit comprising a pair of electrically insulated windings trically opposite terminals of each of said windings being connected to a different one of said circuits, said. windings having 'a substantial mutualinductance and having suificient interwinding capacitance to constitute a tuned circuit resonant to the frequency of said constant voltage circuit.

6. In combination, a constant voltage alternat I ing current circuit, a second circuit, and a device for supplying. alternating' current of constant value to said second circuit from said constant ings being connected to a diflerentone of said circuits, said windings being dimensioned so that there are afforded mutually disposed surfaces-to form sufficient inter-winding capacitance to constitute withsaid mutual inductance a tuned circuit resonant to the frequency of said constant voltage .circuit.

comprising a pair of electrically insulatedwind- 7. A device for effecting the transfer of energy a between a constant-voltage alternating current circuit and a constant current alternating currentcircuit comprising a pair of electrically insulated windings being wound to have an appreciable 'mutual inductance and having surfaces inproximity to afford inter-winding capacitance which together with said inductance constitutes rent circuit comprising a pair of electrically insulated windings each having electrically opposite terminals thereof connected to a diiferent one of the circuits and being wound to have an appreciable mutual inductance, said windings being dimensioned to" provide surfaces in proximity to afford inter-winding capacitance which vtogether with said inductance constitutes a tuned circuit resonant to the frequency of said constant voltage circuit to effect said transfer, said interwinding capacitance being eifective as a series capacitance relative to the flow of current through said windings. 1

which together with said inductance constitutes a tuned circuit for transforming constant voltage alternating current to alternating current of constant value, said windings being dimensioned to be resonant to the frequency of said first mentioned circuits.

10. In combination, an alternating current supply circuit, a load circuit, and a transformer ings being wound to have a substantial mutual inductance and being disposed relative to each other to have sufficient inter-winding capaai tance which together .with said inductance constitutes a. tuned circuit resonant to thefrequency.

of said constant voltage circuit'for efl'ectin'g transformation of constant voltage alternating, current to alternating current of constant value and means for controlling the magnitude of the constant current alternating current.

11. In a combination, an'alternating current prising a magnetic core member, a pair of electrically insulated windings associatedwith said core member andarranged to have a substantial mutual inductance, said windings having sufficient inter-winding capacitance which together with said inductance constitutes a tuned circuit resonant to the frequency of said supply circuit for effecting transformation of constant voltage alternating current to alternating current of constant value, and means for establishing in said core member a 'unidirectional magnetomotive force to control the value of constant current which is transmitted to said load circuit.

12. In combination, an alternating current supply circuit, a load circuit, a transformer comprising a magnetic core member, a pair of electrically insulated windings associated with said core member and arranged to have a substantial mutual inductance,- said' windings having sufficient inter-winding capacitance which together with said inductance constitutes a tuned circuit resonant to the frequency of said supply circuit for effecting transformation of constant voltage alternating current to alternating current of constant value, and means for saturating said core member to control the value of'constant current which is transmitted to said'load circuit.

WILLIAM A. DODGE, Administrator of the Estate of Camil A. Sabbah,

Deceased.

' LYSLE W. MORTON.

supply circuit, a load circuit, a transformer com Certificate of Correction I A v Patent No. 2,168,173 I August 1 ,1939.1"

.WILLIAM A. DODGE, ADMINISTRATOR OF CAMI'L A. SABBAH, f 4 DECEASED; ET AL. 4 r v v It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows: Page 3, first c'olur'nn,- line 38, for

' at read as; line 60, before the equation beginning with 1 xa( =bl) 2xl b=+bt+ +b,

insert the following I i The currentequatlgns may be written as:

af-fifth v a= 4+ a v (4 I a =a n i 5 to (2+ a =3 +b (9 a n =3 1: +b 1| (-2) (r 8 in =a a 1|.

' (nn= n+ z n 0+ l Using the equations of Groups 4 and 5, the currents represented by the in quantities can be eliminated from Equation 2 and the groups 0 EquationsB, as follows: 1

' x b (2a) 2 (2+1) A and second column, line 3,9, beginning with the words The current equations strike out all to and including the equation I v I jE=x;b nx (b +b -lc in lines 63 to 68 inclusive; and that the said Letters Patent should be read withthese corrections therein that the same may conform to the record of the case in the Patent Signed and sealed this 26th day of September, A. D. 1939.

HEN'RY VAN ARSDALE, Acting Commissioner of Patents. 

